.d1{
    border: 1px solid #ccc;
    width: 500px;
    display: flex;
    justify-content: space-between;

    > #p1{
        background:pink;
        width: 200px;
        height: 100px;

        span{
            color: blue;

            &:hover{  //  &相当于是this
                color: red;
            }
        }
    }

    .d2{
        background:#ccc;
        
        span{
            color: green;
        }
    }
}